The present invention relates generally to the art of fluid control valves. More specifically, the invention pertains to an improved direct operated, two-way solenoid valve for regulating the flow of hydraulic fluid, where the valve balances hydraulic forces to permit increased flow rates and produce fast acting operation at reduced noise levels.
Hydraulic shock absorbers are used in vehicle suspension systems to dampen spring oscillations caused by uneven road surfaces or vehicle accelerations. The shock absorbers commonly include a piston slidably mounted within a cylinder. Dampening occurs as fluid is forced through orifices and relief and check valves of the shock absorber.
Shock absorbers have also included electro-magnetic valves which provide a parallel flow path through the chambers of the shock absorber. See e.g., U.S. Pat. No. 4,785,920 issued Nov. 22, 1988, entitled "Hydraulic Adjustable Shock Absorber" and German Pat. No. 1,242,945, issued June 22, 1967. These electro-magnetic valves are located within bypass connections between the working chambers of the shock absorber. Fluid flow through the bypass connection has been selectively controlled by opening or closing the valve.
Hydraulic flow forces within this type of valve increase dramatically in response to an increase in the flow rate through the valve. Small, fast-acting valves are generally limited to a low range of flow rates because their operation is adversely affected by intense hydraulic forces. Alternatively, present valves capable of high flow rates are designed with large housings and components.
It can therefore be seen that a need exists for an improved electromagnetic valve that is small and capable of relatively large flow rates. It can also be seen that such a valve should also be able to shift quickly between open and closed positions without generating significant noise levels.